The invention relates to flexible magnetic disks and more particularly to disk-jacket assemblies in which such disks are rotatably disposed in jackets of more rigid material.
It has previously been proposed that a flexible magnetic disk be rotatably disposed in a containing jacket of more rigid material with the internal surfaces of the jacket having affixed thereon a porous dusting fabric or wiper for maintaining the disk free of contaminant that might interfere with reliable data transfer between a transducer and the disk. The two jacket thicknesses are provided with registering radially extending slots extending also through the dusting fabric, and a transducer may extend through one of the slots into contact with the disk, while a supporting pressure pad may extend through the other slot to support the disk, for data transfer with respect to the disk. Alternately, two opposite transducers may extend through the slots into data transferring contact with the disk. Such constructions are shown in Flores et al, U.S. Pat. No. 3,668,658, Huffine et al, U.S. Pat. No. 4,038,693 and Castrodale et al, U.S. Pat. No. 4,089,029.
In the production of such disk-jacket assemblies, it has been common to bond a layer of the porous dusting fabric to one surface of a blank of the more rigid jacket material and then punch through both the jacket material and fabric in a single stroke to form the slots. This resulted in the edges of the fabric being coincident with the edges of the slots and resulted also in fibers from the fabric migrating or extending from the fabric into the slots on disk rotation thus causing unreliable data transfer by the transducers extending through the slots into contact with the disk. These trouble causing fibers in the data transfer slots of the jacket occurred particularly when overused dulled punches were used, resulting in undue fraying of the fabric.